Oxidative Degradation of Quinoline Using Nanoscale Zero-Valent Iron Supported by Granular Activated Carbon

Abstract

The nano zero-valent iron supported granular activated carbon (nFe0/GAC or 2.5%-nFe0/GAC) was synthesized by the liquid chemical reduction method and further used for the oxidative degradation of quinoline. The 2.5%-nFe0/GAC was characterized by various techniques such as Brunauer-Emmett-Teller (BET) surface area, Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), and field emission scanning electron microscopy (FE-SEM). It was ascertained that iron is of zero state and well dispersed on GAC. The 2.5%-nFe0/GAC exhibited an H4 type hysteresis loop with a surface area of ∼240 m2/g. The kinetic study reveals that quinoline degradation follows the pseudo–first order. At optimum conditions of pH=4, m=7.5 g/L, Co=100 mg/L, and T=303 K, it was observed that (1) ∼93% of quinoline and ∼63% of total organic carbon (TOC) removal is obtained, (2) iron leaching is within the permissible limit, and (3) it requires ∼63±5 min for completion of the half-life of quinoline. The activation energy is ∼22.4 kJ/mole, which indicates that quinoline removal is controlled by a chemical surface reaction. The degradation by-products of quinoline were analyzed. The mass fragments (of m/z=146 and 178) due to hydroxylation were obtained, which were further reduced into low m/z fragments, which may lead to mineralization of quinoline.